Real-Time Imaging of Self-Organization and Mechanical
Competition in Carbon Nanotube Forest Growth
Viswanath Balakrishnan
Mostafa Bedewy
Eric R. Meshot
Sebastian W. Pattinson
Erik S. Polsen
Fabrice Laye
Dmitri N. Zakharov
Eric A. Stach
A. John Hart
10.1021/acsnano.6b07251.s003
https://acs.figshare.com/articles/media/Real-Time_Imaging_of_Self-Organization_and_Mechanical_Competition_in_Carbon_Nanotube_Forest_Growth/4312433
The
properties of carbon nanotube (CNT) networks and analogous
materials comprising filamentary nanostructures are governed by the
intrinsic filament properties and their hierarchical organization
and interconnection. As a result, direct knowledge of the collective
dynamics of CNT synthesis and self-organization is essential to engineering
improved CNT materials for applications such as membranes and thermal
interfaces. Here, we use <i>real-time</i> environmental
transmission electron microscopy (E-TEM) to observe nucleation and
self-organization of CNTs into vertically aligned forests. Upon introduction
of the carbon source, we observe a large scatter in the onset of nucleation
of individual CNTs and the ensuing growth rates. Experiments performed
at different temperatures and catalyst particle densities show the
critical role of CNT density on the dynamics of self-organization;
low-density CNT nucleation results in the CNTs becoming pinned to
the substrate and forming random networks, whereas higher density
CNT nucleation results in self-organization of the CNTs into bundles
that are oriented perpendicular to the substrate. We also find that
mechanical coupling between growing CNTs alters their growth trajectory
and shape, causing significant deformations, buckling, and defects
in the CNT walls. Therefore, it appears that CNT–CNT coupling
not only is critical for self-organization but also directly influences
CNT quality and likely the resulting properties of the forest. Our
findings show that control of the time-distributed kinetics of CNT
nucleation and bundle formation are critical to manufacturing well-organized
CNT assemblies and that E-TEM can be a powerful tool to investigate
the mesoscale dynamics of CNT networks.
2016-11-23 00:00:00
CNT walls
growth rates
growth trajectory
filamentary nanostructures
mesoscale dynamics
carbon nanotube
Mechanical Competition
catalyst particle densities show
CNT synthesis
carbon source
CNT networks
Real-Time Imaging
CNT nucleation
time-distributed kinetics
Carbon Nanotube Forest Growth
CNT density
filament properties
transmission electron microscopy
CNT materials
density CNT nucleation results
influences CNT quality
E-TEM
bundle formation
CNT assemblies
CNT nucleation results
findings show